Jessica Broadbent, who lives 14 miles from the plant, is planning a protest.

"I want them to have transparency," Broadbent told FOX 13 News.

Melanea Wood lives only a mile and a half away and is one of several whose water comes from a well.

"I am this close, I have young kids, are they going to be sick?" she asked.

The DEP admitted Friday it has known about the sinkhole since it opened on August 27, but didn't tell the public. DEP insists it has been monitoring the situation every day, and that Mosaic met its obligation to tell the DEP immediately.

In a statement, the DEP explained why the agency didn't go public.

"Should there be any indication of offsite migration of contaminated groundwater, rules require notification of affected parties. However, to date, there is no evidence of offsite movement or threat to groundwater supplies," a representative told FOX 13 News.

Mosaic representatives gave a similar statement.

"We know the contamination has not migrated beyond the immediate area of the water loss incident, so there's not an urgency," said David Jellerson, a spokesman for the company.

That explanation though, does not hold water with neighbors.

"Why wasn't anybody transparent enough to just say, 'you know what, a sinkhole has happened, we don't know what is going on, we are working [on it]?'" asked Broadbent. "They could [have shown] an active effort instead of a massive cover-up, because that's what this looks like."

Mulberry's representative on the Polk County Commission, Melany Bell, is disappointed as well. While she says it has typically been an environmentally conscious company, she says Mosaic only told her two days ago, after the company became aware news stations were going to cover the story.

She also says Mosaic didn't tell her it first happened three weeks ago.

"If there is any type of contamination, any threat, the neighbors should have been notified," she said.

Mosaic says they have started what could be a months-long process to pump the contaminated water out of the ground. USF environmental science professor Philip van Beynen says it is unlikely they will be able to get out all of the contaminated water.

He does say that the contaminated water will likely be diluted, and does not expect the problem to stick around for years.

"You do have dilution. The Florida aquifer isn't just a stagnant pool of water. It actually does flow. It is moving from north to south slowly. Therefore, you are going to have a dilution factor, water is going to be moving away from that area. So, no, it is not going to be a decades-long problem," said van Beynen.

Broadbent says several dozen people have signed up to protest Saturday morning at Mulberry city hall.

"These things pollute, pollute our drinking water. How can I not be concerned?" she said.

The Polk County government was also aware of the incident but said they did not go public because it is under the DEP's purview.